The invention relates to a system comprising a vehicle and an induction charging unit, the induction charging unit having a primary coil and the vehicle having a secondary coil and, during a charging operation and in a charging position, electric power being inductively transmissible from the primary coil to the secondary coil, in the charging position, the secondary coil being situated in a preferred spatial position area with respect to the primary coil.
Vehicles having an electrified drive train usually have a charging interface to an external charging source. The transmission of electric power in order to, for example, charge an electro-chemical energy accumulator of the vehicle, usually takes place in a wired or inductive manner.
In the case of wired charging methods, the vehicle has to be connected by way of a charging cable with the external charging source, such as a charging station, in order to carry out a charging operation. In the case of inductive charging methods, the power transfer takes place by way of an electromagnetic exciter field of a vehicle-external primary coil to a vehicle-side secondary coil by way of electromagnetic induction at the secondary coil. The transmission efficiency of the electric power in this case is a function of the relative spatial position of the secondary coil with respect to the primary coil. In a preferred position area of the secondary coil relative to the primary coil, the fraction of the exciter power, which occurs as a power loss during the charging, is approximately minimal.
Bringing the secondary coil into the charging position is the object of the state of the art. International Patent Document WO 2011/006884 A2, for example, describes an electronic positioning aid for a vehicle having a primary coil, which positioning aid utilizes the reflection characteristics of a housing of the primary coil situated on the ground.
It is an object of the present invention to describe an improved system which comprises a vehicle and an induction charging unit, the induction charging unit having a primary coil and the vehicle having a secondary coil and, during a charging operation in a charging position, electric power being inductively transmissible from the primary coil to the secondary coil, in which case, in the charging position, the secondary coil is in a preferred spatial position area with respect to the primary coil.
Advantageous embodiments and further developments of the invention are indicated in the dependent claims.
According to the invention, the system for adjusting the charging position by an electromagnetic distance and angle measuring by means of triangulation detects a location position, which describes a time-dependent spatial position of the secondary coil with respect to the primary coil, and, by means of the location position and the charging position, the system detects at least a partial travel trajectory, along which the location position of the charging position can be approximated.
In the charging position, the secondary coil is situated with respect to the primary coil in a spatial position that is preferred in such a manner that, in this position, the efficiency of the electric power transmitted between the two coils is approximately maximal.
According to a preferred embodiment of the invention, the vehicle has at least two low-frequency receiving antennas and the induction charging unit has at least two low-frequency transmitting antennas for the electromagnetic distance and angle measuring.
According to an alternative embodiment, the vehicle has at least one low-frequency receiving antenna and the induction charging unit has at least two low-frequency transmitting antennas for the electromagnetic distance and angle measuring.
According to a further alternative embodiment, the vehicle has at least two low-frequency receiving antennas and the induction charging unit has at least one low-frequency transmitting antenna for the electromagnetic distance and angle measuring.
This means that, on the vehicle side, at least one low-frequency receiving antenna and, externally of the vehicle, at least one low-frequency transmitting antenna is situated, the total number of low-frequency antennas of the system for the distance and angle measuring amounting to at least three.
Furthermore, the vehicle has a charging control device, the charging control device comprising a first high-frequency communication unit, and the charging control device being assigned to the at least one receiving antenna of the vehicle as a measuring unit for the electromagnetic distance and angle measuring, and measuring induction signals of the at least one receiving antenna.
Furthermore, the induction charging unit has an induction control device, the induction control device comprising a second high-frequency communication unit, and the induction control device driving the at least one transmitting antenna. This means that the at least one transmitting antenna is operated by the induction control device.
According to another embodiment of the invention, the vehicle has at least two low-frequency transmitting antennas and the induction charging unit has at least two low-frequency receiving antennas for the electromagnetic distance and angle measuring.
As an alternative to this embodiment, the vehicle has at least one low-frequency transmitting antenna and the induction charging unit has at least two low-frequency receiving antennas for the electromagnetic distance and angle measuring.
According to a further alternative of the invention, the vehicle has at least two low-frequency transmitting antennas and the induction charging unit has at least one low-frequency receiving antenna for the electromagnetic distance and angle measuring.
This means that, according to this embodiment, on the vehicle side, at least one low-frequency transmitting antenna and, externally of the vehicle, in the area of the charging unit, at least one low-frequency receiving antenna is situated, the total number of low-frequency antennas for the distance and angle measuring amounting to at least three.
Furthermore, the vehicle has a charging control device, the charging control device driving at least one transmitting antenna, and the charging control device comprising a first high-frequency communication unit.
In addition, the induction charging unit has an induction control device, the induction control device comprising a second high-frequency communication unit, and the induction control device being assigned to the at least one receiving antenna as a measuring unit for the electromagnetic distance and angle measuring, and measuring induction signals of the at least one receiving antenna.
According to a particularly preferred embodiment of the invention, the measured induction signals can be transmitted between the induction control device and the charging control device, and the charging control device or the induction control device, as the arithmetic unit, detects, by means of induction signals, which are measured, outputted and transmitted to the arithmetic unit, the location position by triangulation.
The measured induction signals are therefore used as input variable for calculating the location position by means of triangulation.
Furthermore, by means of the calculated location position, the charging control device or the induction control device or a further control device of the vehicle detects a travel trajectory, and the vehicle automatically carries out a driving maneuver corresponding to the travel trajectory, or the vehicle informs a driver of the vehicle by way of a suitable human-machine interface concerning a driving maneuver corresponding to the travel trajectory.
The establishing of the charging position takes place in that first one of the two high-frequency communication units sends a coded search signal to the other of the two high-frequency communication units, and the other high-frequency communication unit receives the search signal and sends a coded confirmation signal back to the high-frequency communication unit. The reception of the confirmation signal triggers an initialization routine between the at least one transmitting antenna and the at least one receiving antenna, which is carried out by the charging control device and by the induction control device. After the initialization routine, the at least one transmitting antenna emits a coded electromagnetic positioning signal, in which case, with respect to the spatial dimension of the transmitting antenna, the magnetic fraction of the positioning signal has a defined field orientation and a defined field intensity. At least one receiving antenna receives the at least one positioning signal of the at least one transmitting antenna, and the charging control device or the induction control device measures a magnetic field vector for the at least one positioning signal, which magnetic field vector is unambiguously assigned to the at least one transmitting antenna by means of the coding of the position signal. The measured magnetic field is transmitted from the induction control device to the charging control device or from the charging control device to the induction control device. According to the triangulation method, the charging control device or the induction control device calculates the local position of the at least one transmitting antenna with respect to the at least one receiving antenna. The calculated location position is used as the input variable for the detection of the travel trajectory by the charging control device, by the induction control device or by an additional control device of the vehicle, along which the location position of the charging position can be approximated.
The steps of this method, which are used for detecting the location position, are repeated in real time during a driving maneuver of the vehicle in order to update the calculation of the location position and of the travel trajectory. When the charging position has been reached, the updated travel trajectory will describe a stopping maneuver. During a stopping maneuver, the vehicle comes to a stop.
An iterative method is thereby described by which the charging position can be taken up, in that alternately and in real time a driving maneuver follows the calculation of the travel trajectory and vice-versa, so that, in the case of several driving maneuvers, the charging position can be reached according to the travel trajectory calculated in an updated manner.
For carrying out a driving maneuver, the driver is assisted by way of a human-machine interface by emitted instructions (for example, “steer left”) or the trajectory is used as an input variable for a drive assistance system which automatically moves the vehicle into the charging position.
The invention is based on the considerations presented in the following:
In a plurality of applications, it is the goal to determine the distance of an object (for example, a vehicle) with respect to another object (for example, a vehicle key). Radio technology in the high-frequency and low-frequency band here offers possibilities to do so in a wireless manner by means of measuring field intensities and run-times of electromagnetic alternating fields. One example are modern locking systems of vehicles, such as a keyless access, in the case of which the vehicle acts as a transmitter and the vehicle key acts as a receiver.
In this case, it is a disadvantage that, for more extensive applications, a mere distance determination between the vehicle and a vehicle-external object is not sufficient. A more extensive application is particularly the precise positioning of a vehicle having an electrified drive train and an inductive charging system in a position area that requires a spatial dimension in any spatial direction of approximately less than 10 centimeters.
A vehicle having an inductive charging system has a vehicle-side charging coil, which is also called a secondary coil and which takes over the function of a receiver coil. The primary coil acts as a transmitter coil and is part of a vehicle-external charging infrastructure. The two coils are called charging coils. For charging an energy accumulator of the vehicle, the two coils are to be mutually spatially brought into a precise position with respect to one another in order to ensure an energy transfer that is as efficient as possible during the charging. This position is called a charging position and, as described above, requires a spatial tolerance of maximally 10 centimeters.
For the spatial positioning of the charging coils relative to one another, i.e. for the positioning of the vehicle relative to the vehicle-external charging infrastructure, it is suggested to either use at least two electromagnetic signals that can be unambiguously identified in order to determine several signals at a receiver and therefore routes of at least two different transmitter positions or to use, on at least two receivers, a signal of one transmitter and therefore two routes with respect to a transmitter position for distance and angle measuring. By means of triangulation, a conclusion can clearly be drawn about the position of the receiver or the receivers with respect to the transmitter or transmitters. By way of the same radio system, in addition, communication signals, which describe, for example, position data can be exchanged on the same frequency or another frequency between the transmitter and the receiver.
As a result, an unambiguous position determination and position guidance of the vehicle with respect to the charging infrastructure within the required tolerance becomes possible for an optimal energy transmission efficiency during inductive charging. The position guidance can take place in an automated manner by the vehicle itself or by driving instructions to the driver of the vehicle.
In the following, preferred embodiments of the invention will be described by means of the attached drawings.
The latter contain further details, preferred embodiments and further developments of the invention.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.